Just wanted to give a quick heads up that, with the next PTR build, we'll be removing Petey Yar (the test NPC that granted the achievements required for 7.2 flying) from Dalaran, and implementing the intended requirements to activate the Class Mount quests.

So, if you want to do any additional testing/experimenting with 7.2 Flying or Class Mounts, you have until the next PTR update to do so!